1. Field of the Invention
The invention relates to a method and an apparatus for electroplating small workpieces.
2. Description of the Related Art
Referring to FIG. 1, a conventional barrel 1 used in an electroplating process is immersed in a plating solution 22 of a plating tank 21. The barrel 1 is formed with a plurality of perforations 14 to permit flowing of the plating solution 22 there through, and includes a conductive piece 13 at the center of the barrel 1, a top opening 15, and a cover plate 16 to openably close the top opening 15. Two transmission gears 12 (only one is shown) are respectively provided on two opposite sides of the barrel 1.
During electroplating, small workpieces 3, such as screws, are put into the barrel 1 via the opening 15, after which the opening 15 is closed by the cover plate 16. The barrel 1 is then immersed in the plating solution 22 of the plating tank 21. The transmission gears 12 are subsequently activated so as to rotate the barrel 1 about a horizontal axis, thereby plating the workpieces 3.
However, loading and unloading of the workpieces 3 from the barrel 1 are time-consuming. In particular, the barrel 1 must be removed from the plating tank 21 and uncovered to unload the electroplated workpieces 3. After unloading, the barrel 1 is loaded with a new batch of workpieces 3 and is then re-immersed in the plating tank 21 to proceed with electroplating. Hence, the efficiency of the aforementioned conventional electroplating process is not high.
FIG. 2 shows another conventional barrel 4 that extends in a plating solution 22 (shown in phantom lines) Through a driving unit 23, the barrel 4 can be activated to rotate along a horizontal axis. The barrel 4 includes a helical partition plate 44 extending along an inner wall face of the barrel 4.
After the workpieces 3 are put into the barrel 4, the barrel 4 is rotated by the driving unit 23, such that the workpieces 3 move forwardly along the lower side of the inner wall face of the barrel 4 and are immersed in the plating solution 22. The electroplating process continues until the electroplated workpieces 3 are moved out of the barrel 4. Although the workpieces 3 can be loaded into or unloaded from the barrel 4 without the need to stop rotation of the barrel 4, since the workpieces 3 are moved along the inner wall face of the barrel 4 through the helical partition plate 44, the tumbling movement of the workpieces 3 is limited so that the platings formed on the workpieces 3 are thin and not uniform.